Treatment of sewage-sludges.



UNITED STATES PAT NT oEEIo J FRANCIS MUDIE SPENCE AND HOWARD sPENoE, OF MANCHESTER, ANDREINHOLD OGKEL, Q

OF LowER WALTON, ENGLAND, ASSIGNORS TO PETER SPENCE- & SONS) LIMITED,

MANCHESTER, ENGLAND.

TREATMENT OF SEWAGE-SLIU'DG-ES."

Specification of Letters Patent.

. Patented Oct. 29, 1907..

Application filed October 28. 1906. Serial No.' 284.908.

To all whom 'Lt may concern:

Be it known that we, FRANCIS MUDIE SPENoE and HOWARD SPENCE, subjects of the King of Great'Britain and Ireland, and residents of Manchester, in the county of Lancaster, England, and RErNHoLD OCKEL, a subject of the Emperor of Germany and the King of Prussia, and resident of Lower Walton, in the county of Chester, England, have invented new and useful Improvements in the Treatment of Sewage-sludges and the Like, of which the following is a specification.

This invention relates to the treatment-40f the recovery of the fatty and other valuable substances it containsof (a), the sludge which is precipitated from liquids containing excrementitious and soapy 1 5 and fatty matters (of which liquids ordinary town se w-.

age is a type) by aluminic sulfate or by ferric. sulfate, by alumino-ferric (a crude form ofsulfate of alumina) or by other similarly acting precipitant v'ith or without the addition of mineral acid, or of (b), the sludge which deposits from such liquids sedimentation without the assistance of precipitants, or of (c), a mixture of such sludges. I

Sludge deposited or produced as above described contains much water (frequently from 90 to 95 per 2 5 cent) and it has before now been known to treat such awatery sludge with a mineral acid to facilitate the subsequent recovery of the fatty matters.

According to our present invention we first-partially dehydrate the sludge by separating from it by known means as much liquid as is practicable. Weeffect this, by first curdling the sludge by heat. This result v 'is probably due to thecoagulation of the albuminous matter present and which largely assists in compacting the solid matter present. We then, after drawing off the liquid which now separates from it on settlement, still further de-hydrate it by hot'pressing it. When operations involving heating are carried out at a sewage or other works-which has a towns refuse destructor we may'obtain from the destru ctor the heat which such 40 operations require. L v

The solidified or largely solidified press cake or other mass yielded by the heat curdling and pressure process we now treat with sufficientmineral acid, preferably sulfuric acid, to dissociate the fatty matters from v the bases present.

The addition of the mineral acid to the press cakeor its equivalent presents inter alia the following material advantages over the addition of acid to the watery sludge as before known. A very much smaller quantity of acid is required to effect the dissociationof the fatty matters from the bases, and the rapid destruction of the filter cloths by the acidified liquid (when the hot pressing or like method is employed) is also avoided.

The acid should be intimately mixed with the cake or mass, as, for example, in a mortar mill, or by other suitable means The quantity of acid required-will depend upon the nature of the material underneatment, but dealing, for example, with the sludge precipitated from ordinary town se wage by alumino ferric and subsequently hot pressed: we-have found that from 50 to 75 kilos-of sulfuric acid of 66% S0 to 1000 kilos of press cake or its equivalent containing about 50% to of solid matter is a suitable quantity.

' We have found that a similar sludge when treated in the dilute watery condition with acid previous to pressing requires a quantity of from to 125 or even more kilos of sulfuric acid per 1000kilos of potential press cake contained .in such watery sludge. The

tracted by means of a suitable solvent. The residue from the extraction process contains valuable iertilizing substances'andforms a useful manure.

cure by Letters Patent is:-

The process of treating sewage sludge or the like for the recovery of fatty or other matters, which consists in precipitating the sludge, curdling the precipitate by'heat.

dehydrating said precipitate by hot pressing, mixing mineralecid with the press cake. and subsequently suitably preparing such acid treated mass and extracting the fatty matte'rs theretrom by means of a suitable solvent.

In testimony whereof we have signed our names to this specificationin the presence of two subscribing witnesses.

' FRANCIS MUDIFLSPENCE.

HOWARD SPENC-IG. REINHOLD OCKEL.

Witnesses: WM. WARREN, .Lis. STEWART Bnoao'roo'r.

. Witnesses to the signature of Reinhold Ockel: W. H. 0. DARLINGTON,

W. C. MARK L.

What we do claim as our invention and desire to se- 

